Mortios is a planet always on the other side of the sun from Nai-Tros, leading many on Nai-Tros to think of it as mere myth.
When somebody or something dies on any other planet their Soul are sent to Mortios where they are given a second chance, here they may atone for all and any sins comitted in life, mainly through labor and hard work.
The surface of Mortios is entirely dry, there are no oceans or lakes as water is not a need for the dead, withered vegetation and the souls and remains of long dead creatures fills the landscape.
Atonement for sins is rewarded by being allowed to enter Utopia, those not allowed are punished severely and doomed to wander the furthest reaches of Mortios.